Add support for vertical videos

[Javierd]

Currently, if you try to play a vertical video (such as a short) the thumbail gets distorted to show the video as a 16:9 video. If you try to play the video on full screen mode it'll play the vertical video horizontally, leaving huge side black borders

[VinzentHubrich]

It is possible to play vertical videos or any other videos that differ from a 16:9 aspect ratio by using the videoAspectRatio and matchFrameAspectRatioToVideo parameters like this:

PodVideoPlayer(
      controller: _podPlayerController,
      videoAspectRatio: _podPlayerController.videoPlayerValue!.aspectRatio,
      matchFrameAspectRatioToVideo: true,
)